Ultrastructural Modifications of the Muscle Coat of the Infundibulum and Ampulla of the Mouse Oviduct During Pregnancy and Post-partum

Abstract

The muscle coat of the upper region of the mouse oviduct undergoes morphological changes in both the muscular and the connective matrix components during pregnancy and the post-partum period. During pregnancy, there is a significant increase in the number of mitochondria and caveolae and in the extension of the smooth endoplasmic reticulum in smooth muscle cells, suggesting the enhancement of their contractile activity. Within two days after delivery, these changes regress completely. The interstitial connective matrix in pregnancy undergoes a de novo genesis of basal lamina-like material and of collagen fibers, which vary in diameter and are irregular in outline. Both these connective components appear in relation to deep, round shaped pits present all along the smooth muscle cell surface. After delivery, characteristic morphological patterns appear associated with the active role which the smooth muscle cells play in resorption and reorganization of the intercellular connective matrix.